An unrolling machine generally includes two spool carrier elements each supporting a spool for a finishing band, that is to say a band feeding a processing machine located downstream, and a spool for a new band intended to be connected end to end to the finishing band at the end of the unrolling of the latter to ensure the continuity of the band feed downstream of the machine.
In the known unrolling machines, the connection of the finishing band to the start of the new band is generally carried out during a temporary stop of the unrolling machine, the finishing band running, so as to ensure the continuity of the unrolling during this temporary period, into a band reserve arranged between the outlet of the unrolling machine and the processing machine located downstream.
Among the known unrolling machines, an unrolling machine is disclosed in the document FR-A-2618769, which consists essentially of two spool carrier towers, the upper portion of which is covered by a bridge structure for accommodation of a band accumulator, and of two assemblies for connection of bands which are at a stop, also known under the name of connection boxes or connection semi-cassettes, each dedicated to a spool carrier tower, that is to say to an unrolling or replacement band rolled on the spool mounted on such a spool carrier tower, and which are mounted so that they are mobile in translation, transversely to the band under the bridge structure.
The connection assemblies are mounted in opposition, each under the bridge structure, in such a manner that they can be moved transversely with respect to the latter, by means of horizontal slide firmly attached to said structure and protruding forward with respect to the latter, and they are firmly attached in translation each to the corresponding tower, in order to be able to follow all the movements of the corresponding tower.
On the surface facing the opposite connection assembly, each connection assembly has a plate provided, on the one hand, with a transverse slot inclined with respect to the horizontal, in which is mounted, movable by means of a jack or a linear motor, a cutting device, and, on the other hand, with several rows of air aspiration holes, or grippers, these holes or grippers being arranged, on the one hand, on both sides of the slot, and, on the other hand, parallel to the lower edge of the plate, which is moreover mounted along one of the horizontal edges thereof, preferably along the lower edge thereof, in a pivoting matter on the box, the pivot shaft of the plate simultaneously forming the support of deflection cylinders of the band to be unrolled.
The connection assemblies have a width that is greater than the largest possible width of the bands to be unrolled, and the plates thereof are, on the one hand, symmetrical with respect to a vertical plane passing between the boxes, and, on the other hand, loaded each on the internal surface thereof by a device for pivoting around the shaft.
A simultaneous actuation of the movement device for each plate has the effect of causing a pivoting of said plates around the shaft thereof and of bringing about a tight application of the central planes containing the transverse slots of said plates with interposition of the finishing band and the new band, as well as of their end to end linking adhesive joint.
This unrolling machine makes it possible to perform a cutting and a precise connection between finishing band and new band with great precision with a brief interruption of the unrolling device, requiring a downstream accumulation.
However, these known unrolling machines do not fully meet the new production requirements which impose greater speeds with a guarantee of perfect connection.
The document FR 2 930 534 proposes a device for cutting and end to end gluing, which makes it possible to ensure reduction of the connection time while at the same time guaranteeing a perfect connection. Such a device is provided for an unrolling machine comprising two spools and consisting essentially of two spool carrier elements supporting said spools and covered on their upper portion by a bridge structure capable of accommodating a band accumulator, and of two assemblies for connection of bands which are at a stop, each assigned to a spool carrier element and arranged symmetrically with respect to the unrolling axis of the bands or to the plane containing said axis. In such a device, each connection assembly, also known under the name of connection box or connection semi-cassette, comprises a station for the preparation and transfer of a joint, a device for holding and cutting the new band or the finishing band, and optionally a means for moving the band connection assemblies closer or father apart.
However, in a machine of the type of the document FR 2 930 534, the device for the preparation and transfer of a joint is complex, and the machine requires a transfer system in order to be able to gain access behind the advancing band. In addition, a machine of this type requires moving the two connection assemblies farther apart from or closer to one another, by translation or rotation, in order to carry out the preparation step, so as to create a sufficiently large area of passage between said assemblies and/or around the latter in order to enable the passage of an operator so that the latter can perform the preparation. The result of this moving closer or apart is the need to provide a large-amplitude area of clearance which is reflected in a large space requirement of the machine.
The document FR 2 332 115 concerns an apparatus for end to end assembling of two bands in order to put a new band at the end of a finishing band, and of which the band ends to be connected by a tape are located in the same plane and separated by a short distance. It includes squeezing means including a squeezing piece comprising a control bar for controlling the end to end position, and cutting and assembly means mounted on carriages that can be moved along an elongate bar. It also includes an accumulation device for temporarily stopping the band during the connection period.
However, an apparatus of the type disclosed by the document FR 2 332 115 or the method used by such an apparatus requires the use of a device for positioning the spools so that the new band is always on the same side of the unrolling band. In addition, this type of apparatus requires a second cutting in order to cut a thin band at the end of the new band and remove it to leave room for the adhesive for the end to end connection. On the other hand, in this type of apparatus, the connection is carried out with a single adhesive or joint, that is to say only with a single piece of adhesive tape, applied to one of the sides or surfaces of the connected bands, which does not enable an effective and solid connection for a thick material, because, in passing over a roller for guiding or driving the band, the adhesive may deteriorate or be torn off.
The aim of the present invention is to overcome at least one of these disadvantages by proposing a method for cutting and connecting two bands end to end and which are at a stop in an unrolling machine, a device for cutting and connecting two bands end to end and which are at a stop for an unrolling machine, making it possible to carry out said method, and an unrolling machine provided with such a device, notably making it possible to obtain a simpler preparation and a reduced space requirement for the device or for the machine which guaranteeing that the connection is maintained intact.